George Orwell once summarised history in terms of technology: the castle defeated the knight, gunpowder defeated the castle, and the cheque-book defeated gunpowder (adding that the machine-gun defeated the cheque-book). Rogerson's subject is an illustration of two of these elements.

He tells the story - and he is an excellent storyteller - of the great battles that occurred in the Mediterranean, "the centre of the world", between Islam and Christianity in the 15th and 16th centuries. Fortresses were becoming obsolete, but they could still be formidable; gunnery was developing, but the bombards quite often blew up, and anyway needed teams of experts and logistical support. The result was a seesaw war on land and sea. Portugal and Spain were carrying the cross into lands, including Morocco, that had been Islamic for centuries. But in the eastern Mediterranean, it was the Ottoman Empire that did the advancing.

In Bodrum, on the south-western coast of Turkey, there is a castle that symbolises it all. It is a very imposing 15th-century construction, put up by the Crusading Order of the Knights of St John (Rogerson calls them the "Knights Hospitallers" and should know better). It was a waste of money. By 1500, thick walls were not enough. To withstand the bombards, you had to shape your fortress like a star, so that the gunners could be fired on from the side; in 1522, threatened with a Turkish siege, the knights understood that they had no long-term hope, and surrendered the Bodrum castle intact. The wisdom of this was shown in the same year, when their far greater fortress, on Rhodes, fell.

Fifty years later, in 1571, the greatest fortress of them all, Othello's Famagusta on Cyprus, also fell to the Turks, after an epic siege that Rogerson describes very well. But the real high point of the period occurred in the same year, at sea, when at Lepanto, off western Greece, the Turkish galleys were shattered by Venetian and Spanish galleys. Until then, the Turks had generally had the better of things, but the Christians had worked out how these clumsy wooden vessels could be adapted to carry heavy bombards, and after a while the Turks could not compete.

So, if you want to pin a date on "the rise of the west", 1571 is as good as any. True, even a century later the western victory was far from being clear-cut, and there is a very good book by John Darwin, After Tamerlane (2007), which destroys the various myths about this: ancient world civilisations in India and China were not so easily overthrown, and the few Portuguese ships, and 3,000 men, that appeared to dominate the south-east Asian world were only harbingers, dependent in the end on the good will or divisions of the locals. Even so, it is quite right for Rogerson to centre his narrative on Portugal, the first and, as it bizarrely turned out, last of the European empires.

In 1415 Ceuta, commanding the Gibraltar Strait on the eastern side, was sacked: the Muslim rulers, in North Africa and Spain, had fallen out, and for lack of bombards could not retake the place. Prince Henry the Navigator then bethought himself as to how Portugal could take control of the gold trade in Morocco, and a process of Portuguese expansion got under way, which meant in the first instance forts all along the Atlantic coast of Morocco and then, for a couple of generations, a Portuguese domination of south-eastern Asia. The lure was the spice trade, on which Portugal's bankers in Florence and southern Germany greatly flourished. Quite fittingly, Rogerson closes his book in 1578, when the last crusade of Portugal was broken at the battle of Ksar el Kebir, and young King Sebastian was killed.

The book has essentially two themes: the rise of Iberian Catholicism on the one side, and that of Ottoman Islam on the other. The narrative is easily followed, and the set-pieces are splendid (especially the Turkish conquest of Cyprus). Rogerson has a weakness for the Islamic civilisations, and they were certainly a great deal more sophisticated than the Christian ones, in which greedy thugs, with a torturing Inquisition in their wake, predominated. Spain expelled its Jews, and then its converted Muslims.

There is an interesting book, Americo Castro's The Spaniards (1980), which discusses what Spain lost: quite suddenly, in the 17th century, the bottom dropped out. What caused this to happen? Counter-reformation Catholicism, or just the exhaustion of that century-plus war with Islam? The French were careful not to be involved in it, and they astutely took up an alliance with the Turks in order to defeat Spain, with the result that much of modern Europe became French, not Spanish.

Rogerson is good on the Turkish side of this. He knows that, all along, the Turks had to fight Persia, which had almost the status of historic enemy. Persia fell under a type of Islam - Shia - that is so different as almost to constitute a different religion. In the early 16th century, in pursuit of religious uniformity, the Ottomans not only fought their own wars of religion against the Persians, but also started persecuting their own Shia, now called Alevis. The Alevis practise an Islam that is almost unrecognisable, in that women are equal and drink is drunk. They are today at the centre of the left-wing parties, and you can recognise them because their music is superb and the men wear great bushy moustaches, whereas the orthodox have neatly clipped little numbers that won't touch their food. Why Persian Shia has gone in such a dramatically different direction, who knows? At any rate, the Ottoman Empire was wrecked as much by its Persian wars as by its European ones. Barnaby Rogerson writes very well, and knows what he is talking about, but you might like him to have thoughts beyond his sultans, corsairs and battles.